First of all, I think if it is inconvenient for my father to have sex education by himself, he can use books or female elders close to his daughter. For example, dad can buy some books about children's physical growth and development, put them in children's rooms, or let children trust female elders, or sisters communicate with their daughters.
The content of sex education for girls is to help girls understand some characteristics of physical development, including some physiological and psychological changes; The second is to educate children about self-esteem, self-love and self-protection, including how to communicate with the opposite sex. Thirdly, it is necessary to help children master some common nursing knowledge during physiological period.
Most importantly, dad's care is really important to children in single-parent families. I admire this father for paying attention to such an important issue!